Adriamycin and its analogs are important cancer chemotherapeutic agents. A number of new anthracycline analogs have been recently synthesized and preliminary data indicates that they differ in important characteristics from the parent compounds. In the current proposal, we plan to study the effect of these new analogs on tumor cell proliferation in vitro and in vivo. We will study drug effects on cell cycle traverse, macromolecular synthesis, cellular ultrastructure and chromosomes, and on tumor cell growth. Laser flow cytometry will be used to study drug induced cell cycle perturbations as well as to detect and quantitate intracellular drug content. Cell cycle phase specific cytotoxicity will be studied in tumor cell populations (G1, S, G2/M) separated by elutriation. On the basis of their intracellular drug fluorescence, cells will be stored in a fluorescence activated cell sorter and analyzed for drug content and effects on clonogenicity. Soft agar colony forming assay (for tissue culture cells and tumor cells from xenografts of human solid tumors in nude mice) will be used for this purpose. We hope to use this information for correlating the intracellular drug content with effects on tumor cell clonogenicity.